This invention relates to a vacuum toilet unit.
In a vacuum toilet system, otherwise known as a vacuum sewer system, a normally-closed discharge valve (or sewer valve) is connected between the outlet of the toilet bowl and the sewer pipe, and a vacuum pump, for example a blower or ejector, is used to establish a considerable pressure difference (typically about 0.3 to 0.5 bar) across the discharge valve. The pressure difference may be established by maintaining the vacuum sewer continuously under partial vacuum or it may be generated in connection with initiating each emptying operation of the toilet bowl. When the discharge valve is opened in response to a flush command, the contents of the toilet bowl are forced almost instantaneously into the sewer pipe and are propelled in plug form at high speed along the sewer pipe towards a sewage collection container. In some instances, the sewage collection container itself is placed under vacuum, and in others, it is not. It will therefore be appreciated that a vacuum toilet functions differently from a conventional water toilet, in which water flowing into the toilet bowl under gravity both removes waste from the toilet bowl and cleans the toilet bowl. A vacuum toilet uses air as a waste transport medium. Generally, a small amount of rinse water is supplied to the toilet bowl in connection with the emptying operation for cleaning the toilet bowl.
A vacuum toilet must include an actuator for its sewer valve and a rinse water supply device together with means for controlling the sewer valve actuator and the rinse water supply device and for adjusting the operation of the sewer valve actuator and the rinse water supply device. Further, starting means for the rinsing and the emptying operation and various safety means, for example means preventing the sewer valve from opening if there is not enough vacuum in the sewer, are required. As a result of all this a vacuum toilet needs more maintenance than a conventional water toilet. It is desirable that all the operation and control means of the toilet should be integrated with the toilet bowl in a toilet unit. Accordingly, the toilet unit must be so built that the operation and control means can easily be maintained in spite of a narrow or otherwise restricted mounting space.
U.S. Pat. No. 5,133,853 mentions that a vacuum toilet may have an outer shell. According to the description, it is of advantage to place all the devices required inside the shell. In this known design maintenance of the toilet has been difficult, because diverse devices have not been accessible without quite a large dismounting.